1. Field of Invention
The present invention relates to a light-emitting diode (LED) lamp and a street lamp using the same, which belongs to the field of lighting technology.
2. Related Art
In the wide areas of outdoor roads and squares, conventional lighting lamps are high-pressure sodium lamps or metal halide lamps. The high-pressure sodium lamps or metal halide lamps have a luminous efficiency of 60-80 lm/W, and have a service life of about 6000 hours (h). Currently, the LED lamps have a luminous efficiency of 100-120 lm/W, and have a service life of up to over 25000 h, and do not contain hazardous metal mercury. With the development of semiconductor technologies, such performance of the lamps has been increasingly enhanced. Thus, in recent years, energy-saving and environment-friendly LED lighting lamps have gradually become popular in the market.
The existing LED lighting lamps mainly have two implementations: one is placing an LED light source (briefly referred to as LED) within a conventional lamp; the other is laying out LEDs uniformly, and using a partial reflector or a partial lens for controlling the light. Unfortunately, the above two implementations still cannot overcome the defects of the conventional lighting lamps as follows. Firstly, the directivity of the illumination is poor. The regionality of the illumination is not obvious, that is to say, the lamp illuminates undesirable regions. Thus, in the case of providing the same luminous flux, the brightness of the region requiring the illumination is decreased. Secondly, the brightness is non-uniform, which results in a phenomenon of being bright at a close area and being dark at a distant area. As a result, the luminance of the distance area cannot reach the standard level, or the luminance of the close area is far beyond the standard level. Due to the non-uniform distribution of the illumination, a light source with a higher power and a higher luminous flux has to be adopted in design, so as to enable dark areas at both sides of the road and between two lamps reach the lighting standard level, thereby meeting the luminance requirements of the dark areas, which results in wastes of electric energy. Thirdly, the glare phenomenon cannot be eliminated. The so-called glare phenomenon refers to that when people observe a certain visual object, a dazzling light-emitting spot existing in the visual field may affect the observing effect, which makes people feel uncomfortable. Fourthly, the heat-dissipation problem is not well solved. Currently, about more than 80% of the energy consumption of the LEDs is converted into heat energy, and the semiconductor elements are not high temperature resistant. A lot of LEDs are concentrated in a relative small space, and the continuously increased heat makes the temperature of the LED chip become excessively high. If the generated heat energy cannot be dissipated timely, the luminous efficiency and the service life of the LED may be severely decreased under a high temperature. In most of the existing LED lamps, radiators are disposed horizontally, which have a poor heat convection effect.
The basic reasons for causing the above defects include that, the prior art cannot make full use of the directionality of LEDs, cannot effectively and reasonably control the light rays generated by the LEDs, and cannot effectively dissipate the heats for the LED lamps.